Clamp device for rubbing machines



Nov. 14, 1950 HQY 2,530,301

CLAMP DEVICE FOR RUBBING MACHINES Filed Sept. 29, 1945:

V I] I /2 l -9 L m m 1 infin- J mz/eWZ r/ JOXMZ 6 3am f9 jgza aii Patented Nov. 14, 1950 CLAMP DEVICE FOR RUBBING MACHINES John B. Hoy, Detroit, Mich, assignor to Sundstrand Machine Tool 00., Rockford, Ill.,' acor poration of Illinois Application September 29, 1945, Serial No. 619,360

This invention relates to clamp device for rubbing machines in which an efi'ective and releasable means is provided for clamping sheets of sandpaper, emery cloth, or other rubbing material to the rubbing shoe of a rubbing machine.

Among the objects of my invention are: to provide a novel and improved clamp device for rubbing machines; to provide an eifective and releasable means for positively clamping sheets of abrasive or rubbing material to the shoe of a rubbing apparatus; and to provide a clamp device of-the type referred to which is rapid in clamping operation, secure in its holding ability, and releasable when desired.

Other objects and advantages will become readily apparent from the following detailed description taken in connection with the accompanying drawings herein.

In the drawings:

Fig. 1 is a top plan view of a clamp device embodying my invention and showing the cam and clip in open position without any sheets of rubbing material applied thereto.

Fig. 2 is a longitudinal vertical section on the line 22 of Fig. 1, the rubbing shoe being shown in edge elevat on.

Fig. 3 is a fragmentary vertical longitudinal section through the plate and one of the clamping devices showing the cam as partially swung toward clamping position in the first operational movement, and taken on the same plane as the right hand end portion of line 22 of Fig. 1.

Fig. 4 is an enlarged longitudinal vertical detailed section also on the line 22 of Fig. 1, but showing both of the cams and cam arms as swung into final clamping position with a plurality of sheets of rubbing material clamped between the plate and the clips.

Fig. 5 is a vertical transverse section on the line 55 of Fig. 4.

While my invention resides in the combination, construction and arrangement of parts illustrated in the accompanying drawings, I have therein, for ilustrative purposes, shown a preferred embodiment and I wish it understood that the same is susceptible of modification and change without departing from the spirit and scope of the appended claims.

Referring more in detail to the drawings my clamp device comprises a supporting plate I, preferably of metal, to which is secured a rubbing shoe 2, of rubber or the like, by threaded studs 3 secured in the rubbing shoe. In the form shown the studs 3 are passed through suitable spaced openings in the plate I and secured 9 Claims. (Cl. 51-189) thereto 'by'nuts or the like 4. The plate 1 is secured in any desired manner to a reciprocating portion of an oscillating machine by studs or the like passed through any suitable. number of holes 5 of the plate.

- In the use of this clamping device any desired number of sheets 6 of sandpaper, emery cloth, or other desirable rubbing material are placed over the bottom face of the rubbing shoe 2 and the ends 1 of such sheets clamped against the upper face of the ends of plate I as will be under;- stood in Fig. 4. There is mounted one of these clamping devices at each end'of the plate I;'and as they are both alike except for being reversed in position, only one of them will b'ei'described in detail. The construction of each of theseclamping devices will now be described.

Upstanding from the upper surface of plate I are a pair of apertured integral-ears S-between which extends a fulcrum pin or shaft 9 held in the apertures of the cars by riveting or' otherwise distorting the ends lll'of the pin on the outside face of the respective ears. Clip II ofsheet metal or other suitable material is provided at its forward or outer edge with a.'gripping flange I2 extending downwardly a short distance toward plate I. The back edge portion of the clip is formed with a slot I 3 extending to approximately mid-position of the clip. The metal of the clip on each side of slot I3 is curled around pin 9 so as to have a limited swinging movement thereon. Coiled around the middle portion of shaft 9 is a coil spring I4 having its free ends l5 and I6 extended to a position beneath the clip I I so that the extended end IE will press upwardly against the under face of clip H to normally urge the same to open position, and the other end l6 will press downwardly upon the closed endof the cam bracket as later more fully described.

Also pivotally mounted upon shaft 9is acam bracket l'l positioned within the slot l3 oi the clip. This cam bracket comprises two upstanding curved, laterally spaced apart arms I8 and i9 integrally connected together at their rear end by a web 26 immediately below the coil's'pr'ing M. Coil spring M is positioned-between the inner faces of the cam bracket arms l3'and l9'as will be understood in Fig. 5. The bottom face of web 20 of the cam bracket I1 is, when the cam is free and the clip open, spaced a sufficient distance upwardly from plate l'to permit the cam bracket to have a limited amount of swinging movement about shaft or pin 9. In order to normally urge the free end of the c'am'bra cket toward theclip there is provided in the web 20 a laterally extending slot 2| which on both ends extends upwardly a slight distance into the side plates l8 and IQ of the cam bracket as shown at 22. Positioned in slot 2| and extended laterally a distance beyond the sides l8 and [9 of the cam bracket is a leaf spring 23 having an upwardly extending bent portion 24 extending between arms [8 and 19 of the cam bracket to hold this spring in position. Because of pressure of the extending ends 25 of this spring against plate I the cam bracket is normally urged to rotate in a forward direction.

Fixed therein and extending laterally between the side arms I 8 and [9 of the cam bracket is a pin 26 upon which is pivotally mounted a cam 21 which is formed of side arms 28 and 29- fixed together by a web 30. Web 30 extends rearwardly to form the cam operating arm 3! for manually operating the cam to swing about pin 26. Cam 21 is formed at its lower forward corner (see right hand side of Fig. 4) with a high portion 32, at which corner, by a suitable pin 33 passing between the side walls is rotatably mounted an anti-friction roller 34 adapted to have rolling contact with the upper surface of clip H as the same is rolled thereover during rotational move- .ment of the cam. Formed in the rear lower corner of the cam, as viewed in the right hand side of Fig. 4, is a high portion 35 which, after the roller 34 has passed over clip I l during rotation of the cam in closing direction, bears against the top face of the clip H. The cam is now in closed position and under the influence of spring 23 the roller 34 and the high portion 35 are forced with considerable pressure against the clip I I to firmly grip the ends of the sheets between the clip and the plate.

During the movement of the cam from the position shown in Fig. 2 to the position shown in Fig. 3, and slightly therebeyond in closing direction, the cam bracket will swing a slight distance away from the clip as soon as the clip flange 12 has contacted the ends of the rubbing sheets, until the axis of rotation of roller 34 is in dead center position. Continued rotation of the cam will cause the cam bracket under action of spring 23 to move a slight distance toward the clip to the position shown at both ends of Fig. 4. The roller 34 and the high portion 35 of the cam are spaced a substantial distance apart and under pressure from spring 23 firmly and positively hold the clip in sheet gripping position and against any possibility of becoming inadvertently loosened. Reverse movement of the cam during the unclamping action will cause a reverse operation of the parts just referred to for loosening the sheets with relation to the clip.

When it is desired to apply sheets of rubbing material over the lower face of the rubbing shoe 2 the cams will be moved to the position shown in Fig. 2, which wil1 cause the clips to stand open and the free ends of the sheets of rubbing material may then be inserted between the lower edge of clip flange I 2 and plate I. When the sheets of rubbing material are assembled in desired position the cam arm 3| of each of the clamping devices will be swung to closed position, which will tightly grip the ends of the sheets of rubbing material between the clip and plate and positively hold them in such position during the rubbing action. Should it be desired to apply new sheets of rubbing material the cam arms 3| may be swung to open position, the used sheets removed, new sheets inserted and the cams again swung to closed position as described above. If desired, holes 36 may be formed in each of the clips to enable inspection of the sheets of rubbing material beneath the clip, as well as to give added resiliency to the clip. From the above it will be seen that my improved clamping devices will clamp the ends of the sheets of rubbing material firmly and positively in position so that there can be no disarrangement of the sheets during the rubbing operation. The structure described will prevent any possibility of the cams inadvertently moving to unlocked position while the rubbing sheets are in use.

I claim:

1. A clamp device for clamping rubbing sheets on the shoe of a rubbing machine, comprising a supporting plate, a clip swingably mounted on said plate, a cam bracket pivotally mounted on said plate and having an arm overhanging the plate, a cam pivoted on the forward end portion of the bracket, an arm extending from said cam for manually rotating the cam to press the front edge of the clip closed, a spring for normally urging the front edge of the clip away from the plate, and sprin means for normally swinging the forward end of the cam bracket toward the clip and resisting movement of the cam bracket away from the clip when the clip front edge is closed and the cam is rotated in tightening direction, said clip having on its outer end a flange adapted to clamp the end of said sheets against said supporting plate.

2. A clamp device for clamping rubbing sheets on the shoe of a rubbing machine, comprising a supporting plate, a clip swingably mounted on said plate, a cam bracket pivotally mounted on said plate and having an arm overhanging the plate, a cam pivoted on the forward end portion of the bracket, an arm extending from said cam for manually rotating the cam to press the front edge of the clip closed, a spring for normally urging the front edge of the clip away from the plate, and spring means for normally swinging the forward end of the cam bracket toward the clip and resisting movement of the cam bracket away from the clip when the clip front edge is closed and the cam is rotated in tightening direction, said cam having two spaced apart high portions with a dwell portion therebetween to hold the clip front edge closed under pressure with the cam closed, said clip being formed of stiff sheet metal having on its outer end a downwardly extending flange bearing against the end of said sheets and clamping them against said plate when the cam is closed.

3. A clamp device for securely holding sheets of rubbing material against the shoe of a rubbing machine, comprising a plate to which the shoe is anchored, said clamp device including a sheet gripper at each end of the plate, each of said sheet grippers comprising a clip rotatably connected to the plate, a spring for normally swinging the clip away from the plate, a cam bracket rotatably connected to the plate on a common fulcrum to that of the clip and having an arm extending over the clip, a spring for normally swinging the front end of the cam bracket toward the clip, and a cam rotatably mounted on the front end portion of the cam bracket, said cam having a high portion which when moved into contact with the clip will hold the clip locked in closed position until the cam is released.

4. A clamp device for securely holding sheets of rubbing material against the shoe of a rubbing machine, comprising a plate to which the shoe is anchored, said clamp device including a sheet gripper at each end of the plate, each of said sheet grippers comprising a clip swingably connected to the plate, a spring for normally urging the clip away from the plate, a cam bracket rotatably pivoted to the plate and having an arm extending over the clip, a spring behind the bracket pivot for normally swingin the front end of the cam bracket toward the clip, and a cam rotatably mounted on the front end portion of the cam bracket, said cam having a high portion which when moved into contact with the clip will hold the clip locked in closed position until the cam is released, said cam also having another high portion which precedes the first mentioned high portion as the cam rotates in tightening direction, said preceding high portion having a roller pivotally mounted thereon for contacting the clip surface.

5. A clamp device as claimed in claim 4 in which each of the cams is provided with a dwell portion between the two high portions, one of said high portions being on one side of the cam dead center and the other on the other side of the cam dead center.

6. A clamp device for rubbing machines, comprising a supporting plate, a clip, a cam bracket pivotally mounted on said plate, a spring for normally swinging the front end of the cam bracket toward the clip, and a cam rotatably mounted on the cam bracket, said cam having two high portions spaced one on each of the two opposite sides of dead center when the cam contacts the clip in closed position, the clip and said cam bracket being pivotally mounted to rotate about a common axis.

7. A clamp device comprising a plate, a clip pivotally mounted on the plate, a spring normally urging the clip to open position, a cam bracket pivotally mounted on the plate adjacent the clip and having a free end extending over the clip, a cam pivotally mounted on said free end, a spring behind the pivotal axis of the bracket normally urging said free endtoward the clip, the cam having an operating handle to manually rotate it and a plurality of circumferentially spaced high portions which when one of them is forced over the clip face to a position forward of the cam axis of rotation causes the cam and cam bracket to lock the clip closed until the cam is forcibly rotated in unlocking position by its operating handle.

8. A clamp device as claimed in claim 7, in which the spring of the cam bracket is located back of the axis of rotation of the bracket and is in the form of a bowed leaf spring extending laterally on both sides of the cam bracket into contact with the plate.

'9. A clamp device as claimed in claim 7, in which the clip and the cam bracket are pivotally mounted to rotate about a common axis.

JOHN B. HOY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 610,759 Keany Sept. 13, 1898 672,408 McAfu Apr. 16, 1901 687,177 Caldwell Nov. 19, 1901 1,034,779 Franzky et al. Aug. 6, 1912 2,242,545 Randolph May 20, 1941 2,464,296 Ekstrom Mar. 15, 1949 FOREIGN PATENTS Number Country Date 22,910 Great Britain Nov. 8, 1905 

